An aerogel is a gel comprised of a microporous solid, in which the dispersed phase is a gas. Structurally, an aerogel is characterized by a monolithic internal structure, which is composed of a nano-scale network of pores and fused colloids. The pore structure of aerogels, as classified by the International Union of Pure and Applied Chemistry (IUPAC), includes three different types of pores: micropores (<2 nm in diameter), mesopores (2-50 nm in diameter), and macropores (>50 nm in diameter) with a majority of the pores falling in the mesopore range.
Typically, production of aerogels involves the sol-gel process. That is, aerogels are derived from a gel (e.g., hydrogel), in which the liquid component of the gel has been replaced with a gas (e.g., “air”), resulting in an ultra-light porous material with extremely low density and low thermal conductivity. To date, commercially available aerogels include microporous silica, carbon-based aerogels, and zeolites.
Current applications for aerogels include catalyzers, particle detectors, thermal insulators, and energy absorbers.